Substrate processing method

ABSTRACT

A substrate processing method of preventing damage to a lower patterned structure includes: forming a first thin film having a certain thickness by performing a first cycle a plurality of times, the first cycle including supplying a first reactant on a structure and purging a residue, and forming a second thin film by changing a chemical composition of the first thin film having the certain thickness.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Application No. 63/049,572, filed on Jul. 8, 2020 in the United States Patent and Trademark Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND 1. Field

One or more embodiments relate to a substrate processing method, and more particularly, to a substrate processing method of patterning a structure formed on a substrate.

2. Description of the Related Art

When a thin film is deposited using plasma on a patterned structure on a substrate, the patterned structure may be damaged by radical active species. For example, in the case of a patterned structure such as a spin-on-hardmask (SOH) including a polymeric material, damage to an SOH film may occur. In more detail, when a thin film is deposited using oxygen on a substrate on which an SOH film is formed, oxygen radical active species are generated by plasma application, and the SOH film under the thin film reacts with an oxygen radical, thereby changing the film quality or causing physical damage to the SOH film. Due to the damage to a lower patterned structure, spacing between patterns may not be constant in a subsequent patterning process.

SUMMARY

One or more embodiments include a method of improving the CD uniformity of a patterning process by preventing damage to a lower patterned structure.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure.

According to one or more embodiments, a substrate processing method includes forming a first thin film having a certain thickness by performing a first cycle a plurality of times, the first cycle including supplying a first reactant on a structure and purging a residue, and forming a second thin film by changing a chemical composition of the first thin film having the certain thickness.

According to an example of the substrate processing method, the first reactant may include a silicon-containing source gas.

According to another example of the substrate processing method, plasma may be applied during at least a portion of the first cycle, and the first reactant may be dissociated by the plasma to adsorb the first thin film on the structure.

According to another example of the substrate processing method, during the first cycle, a second reactant that is not reactive with the structure is supplied, and the first thin film may be densified by the second reactant.

According to another example of the substrate processing method, a second cycle is performed a plurality of times during the forming of the second thin film, wherein the second cycle may include supplying a third reactant on the first thin film having the certain thickness, inducing a reaction between the first thin film and the third reactant by applying plasma, and purging a residue.

According to another example of the substrate processing method, the third reactant includes oxygen, and during the inducing of the reaction, the first thin film may be oxidized.

According to another example of the substrate processing method, the third reactant may have reactivity with the structure.

According to another example of the substrate processing method, the first thin film may have a thickness greater than or equal to a certain thickness which allows a loss of the structure that occurs while the third reactant reacts with the first thin film to be less than a certain value.

According to another example of the substrate processing method, the certain thickness may be at least 15 Angstroms.

According to another example of the substrate processing method, the residue purged during the second cycle may include at least one of CH₄, C₂H₅, N(C₂H₅)₂, CO₂, NO, H₂O, and H₂.

According to another example of the substrate processing method, the first thin film includes a mixture of elements constituting the first reactant, and the first thin film may be formed by adsorbing the mixture on the structure.

According to another example of the substrate processing method, the first thin film may include a chemical bond formed by one element of the mixture reacting with at least one of elements constituting the structure.

According to another example of the substrate processing method, the substrate processing method may further include removing at least a portion of the second thin film to form a spacer pattern for the structure, removing the structure, and patterning a lower structure using the spacer pattern as a mask.

According to another example of the substrate processing method, the spacer pattern may include a first protrusion, a second protrusion, and a third protrusion protruding from the lower structure, and a difference between a first distance between the first protrusion and the second protrusion and a second distance between the second protrusion and the third protrusion may be less than 5 Angstroms.

According to another example of the substrate processing method, the substrate processing method may further include forming a third thin film having the same component as that of the second thin film on the second thin film.

According to another example of the substrate processing method, the substrate processing method may further include exposing the structure by performing etch-back on the second thin film and the third thin film, removing the structure, and patterning the lower structure using remaining portions of the second thin film and the third thin film as a mask.

According to another example of the substrate processing method, a third cycle is performed a plurality of times during the forming of the third thin film, wherein the third cycle may include supplying the first reactant on the second thin film, purging residue of the first reactant, supplying the third reactant under a plasma atmosphere, and purging a residue of the third reactant.

According to one or more embodiments, a substrate processing method includes forming a first thin film by supplying a first reactant and a second reactant on a substrate having a patterned structure, supplying a third reactant, and converting the first thin film into a second thin film.

According to an example of the substrate processing method, the substrate processing method may further include forming a third thin film on the second thin film by supplying the first reactant and the third reactant.

According to one or more embodiments, a substrate processing method includes forming a first thin film of a certain thickness adsorbed on the patterned SOH structure by performing a first cycle a plurality of times, the first cycle including supplying a silicon-containing source gas on a patterned spin-on-hardmask (SOH) structure and purging a residue, forming a second thin film by changing a chemical composition of the first thin film by performing a second cycle a plurality of times, the second cycle including supplying a reaction gas that is reactive with the patterned SOH structure and reactive with the silicon-containing source gas and purging a residue, and forming a third thin film having the same component as that of the second thin film on the second thin film by performing a third cycle a plurality of times, the third cycle including supplying the silicon-containing source gas and supplying the reaction gas.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIGS. 1 to 6 are cross-sectional views illustrating a method of manufacturing a semiconductor device according to embodiments;

FIGS. 7 to 10 are views illustrating a substrate processing method according to embodiments;

FIG. 11 is a view illustrating damage to an underlying SOH film due to an oxygen radical and associated problems when a SiO₂ film is deposited by supplying the oxygen radical on a patterned structure in a patterning process;

FIG. 12 is a flowchart illustrating a method capable of minimizing loss or deformation of a lower film when depositing a thin film using an active radical on a patterned structure;

FIG. 13 is a view illustrating a substrate processing method according to embodiments;

FIG. 14 is a flowchart of a substrate processing method according to embodiments; and

FIG. 15 is a graph illustrating the degree of loss of an underlying SOH film for each thickness of a first thin film.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

Hereinafter, one or more embodiments will be described more fully with reference to the accompanying drawings.

In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to one of ordinary skill in the art.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes”, “comprises” and/or “including”, “comprising” used herein specify the presence of stated features, integers, steps, processes, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, processes, members, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, etc. may be used herein to describe various members, components, regions, layers, and/or sections, these members, components, regions, layers, and/or sections should not be limited by these terms. These terms do not denote any order, quantity, or importance, but rather are only used to distinguish one component, region, layer, and/or section from another component, region, layer, and/or section. Thus, a first member, component, region, layer, or section discussed below could be termed a second member, component, region, layer, or section without departing from the teachings of embodiments.

In the disclosure, “gas” may include evaporated solids and/or liquids and may include a single gas or a mixture of gases. In the disclosure, a process gas introduced into a reaction chamber through a shower head may include a precursor gas and an additive gas. The precursor gas and the additive gas may typically be introduced as a mixed gas or may be separately introduced into a reaction space. The precursor gas may be introduced together with a carrier gas such as an inert gas. The additive gas may include a dilution gas such as a reaction gas and an inert gas. The reaction gas and the dilution gas may be mixedly or separately introduced into the reaction space. The precursor may include two or more precursors, and the reaction gas may include two or more reaction gases. The precursor may be a gas that is chemisorbed onto a substrate and typically contains metalloid or metal elements constituting a main structure of a matrix of a dielectric film, and the reaction gas for deposition may be a gas that is reactive with the precursor chemisorbed onto the substrate when excited to fix an atomic layer or a monolayer on the substrate. The term “chemisorption” may refer to chemical saturation adsorption. A gas other than the process gas, that is, a gas introduced without passing through the shower head, may be used to seal the reaction space, and it may include a seal gas such as an inert gas. In some embodiments, the term “film” may refer to a layer that extends continuously in a direction perpendicular to a thickness direction without substantially having pinholes to cover an entire target or a relevant surface, or may refer to a layer that simply covers a target or a relevant surface. In some embodiments, the term “layer” may refer to a structure, or a synonym of a film, or a non-film structure having any thickness formed on a surface. The film or layer may include a discrete single film or layer or multiple films or layers having some characteristics, and the boundary between adjacent films or layers may be clear or unclear and may be set based on physical, chemical, and/or some other characteristics, formation processes or sequences, and/or functions or purposes of the adjacent films or layers.

In the disclosure, the expression “containing a Si—O bond” may be referred to as characterized by a Si—O bond or Si—O bonds having a main skeleton substantially constituted by the Si—O bond or Si—O bonds and/or having a substituent substantially constituted by the Si—O bond or Si—O bonds. A silicon oxide layer may be a dielectric layer containing a Si—O bond, and may include a silicon oxide layer (SiN) and a silicon oxynitride layer (SiON).

In the disclosure, the expression “same material” should be interpreted as meaning that main components (constituents) are the same. For example, when a first layer and a second layer are both silicon nitride layers and are formed of the same material, the first layer may be selected from the group consisting of Si₂N, SiN, Si₃N₄, and Si₂N₃ and the second layer may also be selected from the above group but a particular film quality thereof may be different from that of the first layer.

Additionally, in the disclosure, according as an operable range may be determined based on a regular job, any two variables may constitute an operable range of the variable and any indicated range may include or exclude end points. Additionally, the values of any indicated variables may refer to exact values or approximate values (regardless of whether they are indicated as “about”), may include equivalents, and may refer to an average value, a median value, a representative value, a majority value, or the like.

In the disclosure where conditions and/or structures are not specified, those of ordinary skill in the art may easily provide these conditions and/or structures as a matter of customary experiment in the light of the disclosure. In all described embodiments, any component used in an embodiment may be replaced with any equivalent component thereof, including those explicitly, necessarily, or essentially described herein, for intended purposes, and in addition, the disclosure may be similarly applied to devices and methods.

Hereinafter, embodiments of the disclosure will be described with reference to the accompanying drawings. In the drawings, variations from the illustrated shapes may be expected as a result of, for example, manufacturing techniques and/or tolerances. Thus, the embodiments of the disclosure should not be construed as being limited to the particular shapes of regions illustrated herein but may include deviations in shapes that result, for example, from manufacturing processes.

FIGS. 1 to 6 are cross-sectional views illustrating a method of manufacturing a semiconductor device according to embodiments.

Referring to FIG. 1, a first layer 110, which is a film to be etched, is formed on a substrate 100. The film to be etched may be an insulating layer such as a silicon nitride layer or a mask layer such as an amorphous carbon layer (ACL) used for patterning a lower layer.

Thereafter, a second layer is formed on the first layer 110. The second layer may include a polymeric material that may be easily removed through an ashing and/or strip process as a hard mask. For example, the second layer may include a spin-on-hardmask (SOH) film or a carbon spin-on-hardmask(C-SOH) film. The second layer is then patterned to expose at least a portion of the first layer 110. Accordingly, the substrate 100 including the first layer 110 as the film to be etched and a first patterned structure 120 formed on the first layer 110 may be provided.

Referring to FIG. 2, a first thin film 130 having a certain thickness is formed on an exposed surface of the first layer 110 and the first patterned structure 120 as the second layer. The first thin film 130 may be formed by performing a first cycle including supplying a first reactant onto the first patterned structure 120 and purging the residue a plurality of times. A thickness of the first thin film 130 may increase as the first cycle is repeated.

In some embodiments, the thickness of the first thin film 130 may be adjusted to achieve a certain purpose. For example, after the first thin film 130 is formed, the first thin film 130 may be changed into a second thin film 135 (in FIG. 3) by reacting with a third reactant. The thickness of the first thin film 130 may be adjusted to prevent damage to the underlying first patterned structure 120, which may occur in a process of changing the first thin film 130 to the second thin film 135 (refer to FIG. 3). This will be described in detail with reference to FIG. 4.

The first reactant used to form the first thin film 130 may include a silicon-containing source gas. In an example, a silicon-containing source gas is supplied onto the first patterned structure 120 so that a silicon-containing material layer adsorbed (e.g., chemically adsorbed) on a structure may be formed as the first thin film 130.

For example, the first reactant may be an aminosilane-based silicon-containing source gas containing an alkyl group such as a methyl group (—C_(n)H_(2n+1)) or an ethyl group (—C_(n)H_(2n+2)). That is, the first reactant may include a silicon source containing a carbon element. Accordingly, a material layer formed by the first reactant may include a silicon element and a carbon element.

In some examples, the first thin film 130 may include a mixture of elements constituting the first reactant. The first thin film 130 may be formed by adsorbing the mixture on the first patterned structure 120.

For example, when the first reactant includes a silicon element and a carbon element, the first thin film 130 including a mixture of the silicon element and the carbon element may be formed. A mixture consisting of the first thin film 130 may include Si source molecular fragments in which a bonding structure between elements is destroyed, or may include individual elements constituting the first reactant (e.g., Si, C, N, or H). In other words, the mixture may be a mixture of weak bonds consisting of weaker physical bonds than chemical bonds.

In some embodiments, plasma may be applied during at least a portion of a first cycle to form the first thin film 130. The first reactant is dissociated by the plasma, and the first thin film 130 may be adsorbed on the first patterned structure 120.

In some embodiments, in order to promote the dissociation of the first reactant and/or densify the first thin film 130, a second reactant may be supplied during the first cycle. For example, during the application of the above-described plasma, a second reactant that is not reactive with the first patterned structure 120 may be supplied. For example, the second reactant may include an inert element such as argon (Ar). By supplying the second reactant, the first thin film 130 may be densified.

In some embodiments, while the first thin film 130 is formed, a portion of the first thin film 130 may react with the underlying first patterned structure 120. For example, the first thin film 130 may include a chemical bond formed by one element of the mixture constituting the first thin film 130 reacting with at least one of elements constituting the first patterned structure 120.

As a more specific example, the first reactant may include a silicon element, and thus the mixture of the first thin film 130 formed by the first reactant may include a silicon element. Meanwhile, the first patterned structure 120 under the first thin film 130 may include an oxygen element. In this case, a portion of the thickness of the first thin film 130 may contain a Si—O bond. In particular, the Si—O bond may be formed in a portion of the first thin film 130 adjacent to the first patterned structure 120.

The Si—O bond is not formed in a process of oxidizing the first patterned structure 120, but is formed by bonding of some of oxygen elements on the top of the first patterned structure 120, for example, some oxygen elements of an O₂-terminated site or dangling bonded oxygen elements, with a silicon component at the top of the first thin film 130. Therefore, the first thin film 130 having the Si—O bond may be formed without damage to the first patterned structure 120.

Furthermore, the Si—O bond may serve as a protective film to prevent damage to the first patterned structure 120 in a subsequent process of changing the first thin film 130 into the second thin film 135. In other words, the silicon oxide layer formed in a partial thickness range of the first thin film 130 is formed without damaging the first patterned structure 120, and the silicon oxide layer may protect the first patterned structure 120 during the subsequent process.

In some embodiments, when the first patterned structure 120 is an SOH structure, a silicon-containing source gas may be supplied on a patterned SOH structure. When a portion of the first thin film 130 is formed due to the supply of the silicon-containing source gas, the residue may be purged. By performing these operations (gas supply and purge) as one cycle and performing the cycle a plurality of times, the first thin film 130 of a certain thickness adsorbed on the patterned SOH structure may be formed.

Referring to FIG. 3, after the forming of the first thin film 130 having a certain thickness, forming the second thin film 135 is performed by changing a chemical composition of the first thin film 130. For example, a third reactive material that is reactive with the first thin film 130 may be supplied. The first thin film 130 may be changed to the second thin film 135 due to the supply of the third reactant.

During the forming of the second thin film 135, a second cycle may be performed a plurality of times. The second cycle may include supplying the third reactant to the first thin film 130 having a certain thickness and purging the residue. In order to promote a reaction between the third reaction material and the first thin film 130, plasma may be applied. That is, during the second cycle, inducing the reaction between the first thin film 130 and the third reactant by applying plasma may be additionally performed.

In an example, the third reactant may include oxygen. In this case, the second thin film 135 may be formed by oxidizing the first thin film 130 during the inducing of the reaction. For example, when the first patterned structure 120 is an SOH structure and a silicon-containing source gas is supplied to form the first thin film 130, a chemical component of the first thin film 130 may be changed (e.g., oxidized) by supplying a reaction gas (e.g., oxygen gas) that is reactive with the silicon-containing source gas.

The third reactant may have reactivity with the first patterned structure 120. For example, as described above, the third reaction material may include oxygen, and thus, when the first patterned structure 120 is an SOH structure, the third reaction material may oxidize the lower layer of SOH structure.

While forming the second thin film 135 by supplying the third reaction material, it is necessary to prevent oxidation of the SOH structure under the first thin film 130. To this end, the first thin film 130 may be formed to have a thickness greater than or equal to a certain thickness. The certain thickness may allow a loss of the underlying first patterned structure 120 that occurs while the third reactant reacts with the first thin film 130 to be less than a certain value. For example, the certain thickness of the first thin film 130 may be at least 15 Angstroms (see FIG. 15).

On the other hand, the number of repetitions of the second cycle may be adjusted to prevent damage to the first patterned structure 120. For example, in case of a second cycle in which an oxygen gas is supplied to oxidize the first thin film 130 of a certain thickness and plasma is applied, excessive repetition of the second cycle may cause oxidation of the first patterned structure 120. Therefore, the second cycle may be repeated within a range in which oxidation of the first patterned structure 120 does not occur. For example, the second cycle may be repeated 1 to 10 times, and in a specific example, the second cycle may be repeated 1 to 5 times (see Table 1 below).

A residue that is purged during the second cycle performed to form the second thin film 135 may include a constituent element of the first thin film 130. For example, the first thin film 130 may include Si source molecular fragments (e.g., Si—N—, Si—C—, Si—H—, and Si—C_(n)H_(2n+1)) in which a bonding structure between elements is destroyed or individual elements (e.g., Si, C, N, and H). In this case, a residue including at least one of CH₄, C₂H₅, N(C₂H₅)₂, CO₂, NO, H₂O, and H₂ may be purged during the second cycle.

Referring to FIG. 4, a third thin film 140 is formed on the second thin film 135. In order to form the third thin film 140, an atomic layer deposition (ALD) process may be used. For example, the third thin film 140 having a desired thickness may be formed by repeating a third cycle including a source supply operation, a source purge operation, a reactant supply operation, and a reactant purge operation a plurality of times. In another example, a chemical vapor deposition (CVD) process using a first reactant and a third reactant may be used to form the third thin film 140. A cyclic CVD process may be used during the CVD process.

In some embodiments using the ALD process, the first reactant described above (e.g., a silicon-containing source gas) may be used as the source, and the third reactant (e.g., a reactive gas that is reactive with a source gas such as an oxygen gas) may be used as the reactant. Therefore, the third thin film 140 may include the same component as that of the second thin film 135.

For example, the third cycle may include supplying a first reactant on the second thin film 135 and supplying a third reactant under a plasma atmosphere. When the ALD process is used to form the third thin film 140, the third cycle may further include purging a residue after the supplying of the first reactant and purging a residue after the supplying of the third reactant.

Referring to FIG. 5, a spacer pattern SP for a structure is formed. To this end, at least a portion of the second thin film 135 may be removed. In more detail, the spacer pattern SP for the first patterned structure 120 is formed by removing at least a portion of the second thin film 135 and the third thin film 140. For example, by performing a wet etching process on the second thin film 135 and the third thin film 140, the spacer pattern SP may be formed by etching back the second thin film 135 and the third thin film 140 formed on the first patterned structure 120.

Referring to FIG. 6, thereafter, the first patterned structure 120 is removed. Therefore, the first layer 110, which is a film to be etched, may be etched using a remaining portion (i.e., the spacer pattern SP) of the second thin film 135 and the third thin film 140 as a mask. As described above, according to some embodiments, patterning of a lower structure may be performed by forming the spacer pattern SP using a thin film having a double structure (i.e., the second thin film 135 and the third thin film 140) and by using the spacer pattern SP as a mask.

In some other embodiments, a spacer pattern SP′ (in FIG. 9) may be formed using only the second thin film 135. In this case, at least a portion of the second thin film 135 will be removed to form the spacer pattern (see FIG. 9). In both a case of forming the spacer pattern SP (in FIG. 5) using a thin film having a double structure and a case of forming the spacer pattern SP′ (in FIG. 9) using only a thin film having a single layer structure, it should be noted that at least a portion of the second thin film 135 is removed to form the spacer pattern.

The spacer pattern SP formed as described above may include a first protrusion P1, a second protrusion P2, and a third protrusion P3 protruding from the first layer 110 as a lower structure. In this case, a difference value between a first interval d1 between the first protrusion P1 and the second protrusion P2 and a second interval d2 between the second protrusion P2 and the third protrusion P3 may be less than 5 Angstroms.

As described above, because a double patterning technology (DPT) spacer pattern is formed by changing the first thin film 130 to the second thin film 135 after forming the first thin film 130 having a sufficient thickness to minimize reactivity with the first patterned structure 120, it is possible to prevent a problem in which a hard mask of a DPT process is damaged. As a result, a mask formed by a residual spacer may have a uniform inner space critical dimension (CD) and outer space CD, and features may be aligned so that a yield of the final product may be improved and good characteristics of the product may be achieved.

FIGS. 7 to 10 are views illustrating a substrate processing method according to embodiments. The substrate processing method according to the embodiments may be a variation of the substrate processing method according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein.

FIGS. 1 to 6 illustrate a process of forming the spacer pattern SP using a thin film having a double structure (i.e., the second thin film 135 (in FIG. 6) and the third thin film 140 (in FIG. 6)), while the embodiments shown in FIGS. 7 to 10 illustrate a process of forming the spacer pattern SP′ using a thin film having a single layer structure (i.e., the second thin film 135).

Referring to FIG. 7, the first thin film 130 having a certain thickness is formed on an exposed surface of the first layer 110 and the first patterned structure 120 as the second layer. In this case, the first thin film 130 may be formed to have a thickness required to form a spacer pattern.

Referring to FIG. 8, the second thin film 135 is formed by changing a chemical composition of the first thin film 130 having a certain thickness. To this end, a third reactant may be supplied, and as described above, by forming the first thin film 130 having a thickness equal to or greater than a certain value, a reaction between the third reaction material and the underlying first patterned structure 120 may be minimized. Furthermore, in the process of forming the first thin film 130, by forming a layer (e.g. a silicon oxide layer) having a chemical bond (e.g. a Si—O bond) between the first thin film 130 and the first patterned structure 120, damage to the underlying first patterned structure 120 due to the supply of the third reactant may be prevented.

Thereafter, as shown in FIG. 9, at least a portion of the second thin film 135 is removed to form the spacer pattern SP′ for the first patterned structure 120. Also, as shown in FIG. 10, the first patterned structure 120 is removed to utilize the spacer pattern SP′ as a mask. A spacer mask of this single layer structure is distinguished from the spacer mask of the double layer structure of the above-described embodiment, but in both cases, it should be noted that it is common in that the first thin film 130 is formed of a mixture of weak bonds having a sufficient thickness and the first thin film 130 is converted into the second thin film 135 to form at least a portion of the spacer mask.

FIG. 11 is a view illustrating damage to an SOH film under a SiO₂ film due to oxygen radical and associated problems when the SiO₂ film is deposited by supplying the oxygen radical on a patterned structure in a patterning process.

In FIG. 11, on a substrate on which a pattern is to be formed, as a mask film for pattern formation on a patterned structure such as an SOH film, the SiO₂ film is uniformly deposited on the SOH film by a PEALD method. Subsequently, through a selective etching process, the patterned structure is removed and the mask film remains, and when the etching process is continued thereafter, the patterned structure is finally left on the substrate.

In an ideal case, the spacings between the mask films, i.e., CDs, are the same (A=B=C). However, in reality, as shown in FIG. 11, the SOH film reacts with an oxygen radical, which is a reaction gas, at the initial stage of deposition of the SiO₂ film, thereby losing the original shape, and the spacing between the mask films, i.e., CDs are different (A≠B≠C), which causes a semiconductor device defect.

Accordingly, the disclosure provides a method capable of minimizing the loss or deformation of a lower layer when depositing a thin film using an active radical on a patterned structure. FIG. 12 exemplarily shows such a substrate processing method. Operations of FIG. 12 may be described as follows.

Operation 101: A substrate on which a patterned structure is formed is mounted on a reactor. The patterned structure may be a mask film for forming a pattern on the substrate. For example, the material of the mask film may be an SOH or a polymeric material for forming the mask film.

Operation 201: A first reactant and a second reactant are supplied on the patterned structure to form a first film. The second reactant may be a material that is not reactive with respect to the first reactant and the patterned structure. In an embodiment, the second reactant may be an inert gas activated by high-frequency power applied to a reaction space, for example, an Ar radical. The first reactant is a material including a thin film constituent material, and may be a liquid material, and may be supplied to the substrate in a vapor state by a carrier gas. In an embodiment, the first reactant may be a source material containing a Si element. The first thin film may be formed while consecutively supplying the first reactant and the second reactant, and this process is repeated several times. In the second operation, because the second reactant has no chemical reactivity with the first reactant, the first thin film to be deposited may include a first reactant dissociated by the applied high-frequency power, such as a constituent material of the source material, and at the same time is densified on the substrate by the second reactant. For example, when the first reaction material is a Si source material containing carbon, nitrogen, and hydrogen components, the first thin film may include Si source molecular fragments in which a bonding structure between constituent elements is destroyed, and/or the first reaction material may include individual Si, carbon, nitrogen, hydrogen elements, random mixtures of the corresponding elements, or a mixture of weak bonds with physical bonding weaker than chemical bonding.

Operation 301: A third reactant is supplied on the first thin film formed in the second operation (step 2). The third reactant is a material having chemical reactivity with the first reactant, and may be, for example, an activated gas containing oxygen.

Operation 401: The first thin film is converted into a second thin film by a chemical reaction between the first thin film formed on the substrate in the second operation (step 2) and the third reactant supplied in the third operation (step 3). In an embodiment, the conversion may be a process of oxidizing the first thin film. For example, when the first thin film is a mixture containing a Si element and the third reactant is an oxygen radical, the second thin film may be SiO₂. In the fourth operation, by-products generated in a reaction between the first thin film and the third reactant are removed and exhausted out of the reactor.

Operation 501: A third thin film is formed on the second thin film. The third thin film may have the same film quality as the second thin film, and for example, the third thin film may be a SiO₂ thin film. The third thin film may be formed by supplying the first reactant and the third reactant alternately and consecutively. In an embodiment, the third thin film may be a SiO₂ film formed by a PEALD method.

FIG. 13 is a view illustrating a substrate processing method according to embodiments. The substrate processing method according to the embodiments may be a variation of the substrate processing method according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein.

Referring to FIG. 13, a substrate is processed using a first reactant, a second reactant, and a third reactant. Hereinafter, it will be described on the premise that the first reactant contains a Si source material (e.g. precursor), the second reactant contains Ar, and the third reactant contains oxygen (02).

Step 1: A protective layer formation step is performed. In Step 1, a first thin film is formed on an SOH patterned structure while alternately supplying a Si source material and an Ar gas. When the Ar gas is supplied, high-frequency power is supplied to a reaction space to dissociate the Si source gas and the Ar gas. Because the Si source material and the Ar plasma are not chemically reactive, the first thin film includes the Si source material dissociated by the applied high frequency power. When the Si source material is an aminosilane gas composed of nitrogen and an alkyl group (C_(n)H_(2n+1)), for example, diisopropylaminosilane (DIPAS), the Si source material may be Si source molecular fragments in which a bonding structure between constituent elements is destroyed, individual Si, carbon, nitrogen, and hydrogen elements, or a mixture of corresponding elements. The Si source material may be a mixture of weak bonds consisting of physical bonding weaker than chemical bonding. However, the very first layer of the Si source material adsorbed on the patterned structure may react with an H-terminate site on a surface of a lower patterned structure to form a —Si—O-chemical bond.

In Step 1, the first thin film may be more densified on the SOH patterned structure due to an ion bombardment effect of an Ar radical. By activating an Ar gas other than an oxygen gas to form the first thin film on the SOH patterned structure, it has a technical effect of preventing deformation of an underlying SOH patterned structure.

Step 1 is repeated several times (m times) to form a first thin film having a certain thickness. A thickness of the first thin film needs to have a thickness in a range that may be converted into a second thin film of a SiO₂ component without deforming an SOH structure when an oxygen radical penetrate into the first thin film, and detailed description thereof will be described later below.

Step 2: After Step 1, an oxygen treatment and oxidation step is performed. In Step 2, while supplying an oxygen gas, the first thin film is converted into the second thin film, that is, a SiO₂ film. When an oxygen gas as a third reactant, is supplied, high-frequency power is applied to the reaction space to form an oxygen radical, and the oxygen radical reacts chemically with Si-bonded molecular fragments in the first thin film to form a SiO₂ thin film. For example, molecular fragments containing Si elements, such as Si—N—, Si—C—, Si—H—, and Si—C_(n)H_(2n+1), and an oxygen radical may react chemically with each other to form a SiO₂ film. As an example of by-products of the chemical reaction, there may be various combinations of by-products such as CH₄, C₂H₅, N(C₂H₅)₂, CO₂, NO, H₂O, H₂, etc., which are purged and removed from the reaction space by an Ar purge gas. Therefore, Step 2 has a technical effect of converting the first thin film into a SiO₂ film while minimizing deformation of an SOH lower film by an oxygen radical due to a certain thickness of the first thin film.

Step 3: SiO₂ film formation after Step 2. In Step 3, a third thin film is chemically deposited on the second thin film. In Step 3, a third thin film of SiO₂ is chemically deposited on the second thin film while alternately and consecutively supplying the Si source material that is the first reactant and the oxygen radical that is the third reactant. It is preferable that the second thin film and the third thin film have the same film quality, and problems such as peeling of the second thin film and the third thin film that may occur in a subsequent heat treatment process may be prevented.

Table 1 below shows an example of experimental conditions under which the above-described embodiment of FIG. 12 is performed.

TABLE 1 Items Conditions Process temperature (° C.) Room temperature to 550° C. (preferably 50° C. to 300° C.) Process pressure (Torr) 1.0 Torr to 5.0 Torr (preferably 2.0 Torr to 3.0 Torr) Si precursor DIPAS (diisopropylaminosilane) Reactant O2 Purge gas Ar First step (protective film forming step) Process time Source supply (S1) 0.05 sec to 2.0 sec (preferably 0.1 sec to 1.0 sec) (sec) Source purge (S2) 0.05 sec to 2.0 sec (preferably 0.1 sec to 1.0 sec) Plasma application (S3) 0.05 sec to 2.0 sec (preferably 0.1 sec to 1.0 sec) Purge (S4) 0.05 sec to 2.0 sec (preferably 0.1 sec to 1.0 sec) Repeat S1 cycle to S4 cycle 50 times to 200 times (preferably 100 times to 150 times) Gas flow rate Source carrier (Ar) 100 sccm to 10,000 sccm (preferably 600 sccm to 1,200 sccm) (sccm) Purge gas (Ar) 1,000 sccm to 10,000 sccm (preferably 3,000 sccm to 6,000 sccm) Plasma conditions RF power (W) 100 W to 1,000 W (preferably 200 W to 400 W) RF frequency 13 MHz to 100 MHz (preferably 27 MHz to 60 MHz) Second step (oxygen treatment and oxidation step) Process time Pre-purge (S5) 0.05 sec to 5.0 sec (preferably 0.5 sec to 5.0 sec) (sec) Plasma application (S6) 0.05 sec to 3.0 sec (preferably 0.1 sec to 2.0 sec) Purge (S7) 0.05 sec to 2.0 sec (preferably 0.1 sec to 1.0 sec) Repeat S5 cycle and S6 cycle 1 time to 10 times (preferably 1 time to 5 times) Gas flow rate Reaction gas (O2) 50 sccm to 1000 sccm (preferably 200 sccm to 500 sccm) (sccm) Purge gas (Ar) 1,000 sccm to 10,000 sccm (preferably 3,000 sccm to 6,000 sccm) Plasma conditions RF power (W) 100 W to 1,000 W (preferably 200 W to 400 W) RF frequency 13 MHz to 100 MHz (preferably 27 MHz to 60 MHz) Third step (SiO₂ film forming step) Process time Source supply (S8) 0.05 sec to 2.0 sec (preferably 0.1 sec to 1.0 sec) (sec) Source purge (S9) 0.05 sec to 2.0 sec (preferably 0.1 sec to 1.0 sec) Plasma application (S10) 0.05 sec to 2.0 sec (preferably 0.1 sec to 2.0 sec) Purge (S11) 0.05 sec to 2.0 sec (preferably 0.1 sec to 1.0 sec) Repeat S8 cycle to S11 cycle 1 time to 10 times (preferably 1 time to 5 times) Gas flow rate Source carrier (Ar) 100 sccm to 10,000 sccm (preferably 600 sccm to 1,200 sccm) (sccm) Reaction gas (O₂) 50 sccm to 1000 sccm (preferably 200 sccm to 500 sccm) Purge gas (Ar) 1,000 sccm to 10,000 sccm (preferably 3,000 sccm to 6,000 sccm) Plasma conditions RF power (W) 100 W to 1,000 W (preferably 200 W to 400 W) RF frequency 13 MHz to 100 MHz (preferably 27 MHz to 60 MHz)

FIG. 14 is a flowchart of a substrate processing method according to embodiments. The substrate processing method according to the embodiments may be a variation of the substrate processing method according to the above-described embodiments. Hereinafter, repeated descriptions of the embodiments will not be given herein.

Referring to FIG. 14, an SOH patterned structure 1 is prepared (14(a)), and a Si source material is supplied to the SOH patterned structure 1 to form a first thin film 2 on the patterned structure 1 (14(b)). Thereafter, an oxygen radical is supplied to convert the first thin film 2 into a second thin film 3 of a SiO₂ component (14(c)). Thereafter, a third thin film 4 of a SiO₂ component is formed on the second thin film 3 (14(d)). By this process, deformation or loss of the SOH patterned structure 1 due to an oxygen radical may be minimized.

FIG. 15 shows the degree of loss of an underlying SOH film depending on the thickness of a first thin film formed according to the above-described process. Referring to FIG. 15, it can be seen that when the first thin film is at least 15 Å, the loss degree of an SOH film is reduced to 5 Å or less, which is an allowable range. Therefore, in the forming of the first thin film performed in the above-described embodiments, it is preferable that the cycle is repeated such that the first thin film has a thickness of at least 15 Å.

In some embodiments, a third thin film may not be additionally formed, and the first thin film may be formed thicker and then converted into a second thin film. In this case, a second reaction material is sufficiently chemically reacted with the first thin film by increasing a time for applying high frequency power or increasing the amount of power.

It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the following claims. 

What is claimed is:
 1. A substrate processing method comprising: forming a first thin film having a certain thickness by performing a first cycle a plurality of times, the first cycle comprising supplying a first reactant onto a structure and purging a residue a plurality of times; and forming a second thin film by changing a chemical composition of the first thin film having the certain thickness.
 2. The substrate processing method of claim 1, wherein the first reactant comprises a silicon-containing source gas.
 3. The substrate processing method of claim 1, wherein plasma is applied during at least a portion of the first cycle, and the first reactant is dissociated by the plasma to adsorb the first thin film on the structure.
 4. The substrate processing method of claim 3, wherein a second reactant that is not reactive with the structure is supplied during the first cycle, and the first thin film is densified by the second reactant.
 5. The substrate processing method of claim 1, wherein a second cycle is performed a plurality of times during the forming of the second thin film, wherein the second cycle comprises: supplying a third reactant on the first thin film having the certain thickness; applying plasma to induce a reaction between the first thin film and the third reactant; and purging a residue.
 6. The substrate processing method of claim 5, wherein the third reactant comprises oxygen, and the first thin film is oxidized during the inducing of the reaction.
 7. The substrate processing method of claim 5, wherein the third reactant is reactive with the structure.
 8. The substrate processing method of claim 7, wherein the first thin film has a thickness greater than or equal to a certain thickness which allows a loss of the structure that occurs while the third reactant reacts with the first thin film to be less than a certain value.
 9. The substrate processing method of claim 7, wherein the certain thickness is at least 15 Angstroms.
 10. The substrate processing method of claim 5, wherein the residue purged during the second cycle comprises at least one of CH₄, C₂H₅, N(C₂H₅)₂, CO₂, NO, H₂O, and H₂.
 11. The substrate processing method of claim 1, wherein the first thin film comprises a mixture of elements constituting the first reactant, and the first thin film is formed by adsorbing the mixture on the structure.
 12. The substrate processing method of claim 11, wherein the first thin film comprises a chemical bond formed by one element of the mixture reacting with at least one of elements constituting the structure.
 13. The substrate processing method of claim 1, further comprising: removing at least a portion of the second thin film to form a spacer pattern for the structure; removing the structure; and patterning a lower structure using the spacer pattern as a mask.
 14. The substrate processing method of claim 13, wherein the spacer pattern comprises a first protrusion, a second protrusion, and a third protrusion protruding from the lower structure, and a difference between a first distance between the first protrusion and the second protrusion and a second distance between the second protrusion and the third protrusion is less than 5 Angstroms.
 15. The substrate processing method of claim 1, further comprising forming a third thin film having the same component as that of the second thin film on the second thin film.
 16. The substrate processing method of claim 15, further comprising: exposing the structure by performing etch-back on the second thin film and the third thin film; removing the structure; and patterning a lower structure using remaining portions of the second thin film and the third thin film as a mask.
 17. The substrate processing method of claim 15, wherein a third cycle is performed a plurality of times during the forming of the third thin film, wherein the third cycle comprises: supplying the first reactant on the second thin film; purging a residue of the first reactant; supplying the third reactant under a plasma atmosphere; and purging a residue of the third reactant.
 18. A substrate processing method comprising: forming a first thin film by supplying a first reactant and a second reactant on a substrate having a patterned structure; supplying a third reactant; and converting the first thin film into a second thin film.
 19. The substrate processing method of claim 18, further comprising forming a third thin film on the second thin film by supplying the first reactant and the third reactant.
 20. A substrate processing method comprising: forming a first thin film of a certain thickness adsorbed on a patterned spin-on-hardmask (SOH) structure by performing a first cycle a plurality of times, the first cycle comprising supplying a silicon-containing source gas on the patterned SOH structure and purging the residue; forming a second thin film by changing a chemical composition of the first thin film by performing a second cycle a plurality of times, the second cycle comprising supplying a reaction gas that is reactive with the patterned SOH structure and reactive with the silicon-containing source gas and purging the residue; and forming a third thin film having the same component as that of the second thin film on the second thin film by performing a third cycle a plurality of times, the third cycle comprising supplying the silicon-containing source gas and supplying the reaction gas. 